Summary (from original application) The hydrocarbon core of a bilayer is normally a strict barrier to the passage of polar or charged solutes. We have discovered a novel class of cationic peptides that efficiently cross this barrier without causing bilayer permeabilization. These peptides are fundamentally different from other classes of membrane active peptides, and may hold the key to understanding how to bypass the barrier of the hydrocarbon core on demand. Our long-term goal is to develop versatile peptide delivery vehicles for systemic delivery of poorly membrane permeable drugs. Peptides with these properties could eliminate the membrane barrier in drug development and thus could transform the field. We have already demonstrated the discovery and characterization of membrane translocating peptides and the sequences and uses have been patented (Wimley et.al. USPTO #8,603,966). In these proof of concept activities we will demonstrate that the family of peptides discovered can deliver useful cargoes to cells. Success here will a major advance in drug delivery as the sequences we identify will have the capability to eliminate the membrane barrier in drug design. Our contacts in the biotech and pharmaceutical industry suggest that such peptides will have significant potential for immediate licensure. Further, the peptides we discover will have generic deliver capabilities, and thus will have utility in small molecule drugs, as well as for larger molecules such as bioactive peptides or peptide nucleic acids, which currently are very difficult to use as drugs because they are not membrane permeable.